The subject invention pertains to bearings and more particularly to an improved bearing structure for supporting the drive shaft of a downhole well drilling motor.
The design of bearing assemblies which will withstand the hostile environments and force loads typically encountered in downhole well drilling presents a continuing challenge to the industry. The extremely high temperatures encountered preclude the successful application of sealed technology as it currently exists. Thus, the prior art has turned to bearing structures exposed to the drilling fluids passing through the downhole motor.
In the prior art, two separate bearings have typically been provided to accommodate the forces on the drive shaft of the downhole motor. The bearings have typically been designed such that one bearing accommodates radial forces and the second, separate bearing accommodates thust loads. Typical bearing materials have included poly-crystalline diamond (PCD), ceramics, and tungsten carbide matrix. Bearing inserts, including PCD faced inserts, have also been employed in prior art designs.
Prior art designs for mounting the bearings in downhole motors have required close manufacturing tolerances, numerous parts and a relatively long assembly time. It has appeared desirable to the inventor to design an improved bearing structure which would considerably reduce tolerance requirements, part count and assembly time while increasing bearing lifetime, and avoiding bearing seal problems.